Решение:
sin(x+pi/4+x-pi/4)/cos(x-pi/4)cos(x+pi/4)=sinx/cosx
4sinxcosx/cos2x=sinx/cosx
sinx=0
x=Пk
4cosx=cos2x
4cosx=2cos^2x-1
(2+-sqrt(6))/2
1+sqrt(6)/2>1
(1-sqrt(6)/2>-1
нет решения
Ответ: x=Пk.
1) 4,01(17,2+32,8):5/3=(4.01*50):5/3=200.5:5/3=401/2*3/5=1203/10=120,3
1/2-1/2²*2 2/3-25*0,03*4=1/2-1/4*8/3-25*4*0,03=1/2-2/3-100*0,03=-1/6-3=
-3 1/6
2) 6у-3х-2у+6х=4у+3х=4*0,25+3*(-2/9)=1+(-2/3)=1-2/3==1/3
3) 10а+5b
4) 21/8:7=3/8=0.375
0.75-0.375=0.375
2.25+0.375=2.625=2 5/8=21/8
21/16:21/8=1/2=0.5
0.5-0.5=0
5) 6х-(2х-(3х-(4х+4)))=6х-(2х-(3х-4х-4))=6х-(2х-3х+4х+4)=6х-2х+3х-4х-4=
3х-4